Volcanic plumes from explosive basaltic eruptions: the case of Mount Etna (Italy)

Snee, Eveanjelene 2021. Volcanic plumes from explosive basaltic eruptions: the case of Mount Etna (Italy). PhD Thesis, Cardiff University. Item availability restricted.

Preview	PDF - Accepted Post-Print Version Download (11MB) | Preview
	PDF (Cardiff University Electronic Publication Form) - Supplemental Material Restricted to Repository staff only Download (166kB)

Abstract

Explosive basaltic eruptions at Mount Etna, Italy, distinguished by a lava fountain surrounded by a tephra plume, have occurred frequently in recent decades. The associated injection of tephra into the atmosphere creates a hazard to local and regional communities. Despite this, the plume dynamics are poorly-understood. To improve the understanding of this phenomena, I investigate coupled tephra plumes – lava fountains through three approaches. First, I develop a new integral model that explicitly considers the denser, coarse inner lava fountain and its effect on the surrounding tephra plume. Depending on the grain-size distribution and partitioning of initial mass flow rate (MFR) into the lava fountain, a coupled tephra plume can go higher or lower than a standard tephra plume for a given initial MFR. Secondly, I examine the relationship between plume dynamics and eruption deposits. While neither the initial MFR from a standard or the newly-developed integral model correlate to the deposit-derived MFR, the modelled MFR at the point above the lava fountain in the newly-developed model does, suggesting that these plumes have significant fallout that is not captured in typical deposit measurements. Specifically, the cone-deposit itself must be considered to account for the discrepancy between the deposit-derived and modelled initial MFRs. Finally, these results are supported by visible-wavelength video analysis of these eruptions. Qualitative analysis shows that lava fountains and tephra plumes are not fully-coupled, that lava fountains occur in the centre of tephra plumes and that surrounding material (volcanic gas and loose particles) are entrained into the plumes. Rotation of the plumes in some eruptions is also examined, although I show that its effect on plume dynamics is insignificant. Determined wind and radial entrainment coefficients are also comparable to those of standard tephra plumes. Together, these findings highlight that lava fountains significantly affect the rise of coupled tephra plumes.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Earth and Environmental Sciences
Funders:	NERC
Date of First Compliant Deposit:	27 January 2022
Last Modified:	27 Sep 2022 01:14
URI:	https://orca.cardiff.ac.uk/id/eprint/146998

Actions (repository staff only)

Edit Item